Carton having metal corrosion inhibiting characteristics



Dec. l2, 1950 c. A. HUTTER 2,534,201

CARTON HAVING METAL coRRosIoN INHIBITING CHARACTERISTICS Filed Nov. l, 1949 @kwam BYM (1%W/ ATTORNEYS.

Patented Dec. 12, 1950 v CARTON HAVING METAL CORROSION -INHIBITING CHARACTERISTICS Clemens A. Hutter, Chicago, Ill., assigner to Nox- Bust Chemical Co., Chicago, lll., a corporation of Illinois Application November 1, 1949, Serial No. 124,852

9 Claims. (Cl. 22S-3.5)

This invention relates to an article of manufacture, such as a carton, separator, wrapper, or the like, characterized by its ability to prevent corrosion of metallic surfaces by elements normally existing in the, atmosphere when the metallic surface is arranged in the near vicinity of the article of manufacture, or preferably when packaged within the article of manufacture if it is a carton or a wrapper.

In my copending application, Serial No. 79,105, illed on March 1, 1949. now Patent No. 2,521,311, description is made of a metal corrosion inhibiting composition formulated of an organic amide and an inorganic metal nitrite, A synergistic effect is secured by the combination of two types of substances in the same composition which gives metal corrosion inhibiting characteristics of far greater magnitude and for an extended length of time than is secured by either substance alone or what might be expected under normal circumstances from the combination of materials. This disproportionate effect is illustrated by practical experiments in the aforementioned application. I have found further evidence of desirable synergistic eifects resulting from the treatment by which the article of manufacture of this invention is prepared, as will hereinafter be pointed out.

Suitable inorganic nitrites are described as including alkali metal nitrites, such as ammonium nitrite, sodium nitrite. potassium nitrite, lithium nitrite, and the like. A more inclusive definition ofv suitable nitrites will include other water soluble nitrites and the nitrites which are mutually soluble with the amide in organic solvents, that is most soluble nitrites.

As described in the aforementioned application, amides which may be used in combination with the nitrites may be described as the monoamides, diamides, and polyamides. The term mono-amide is meant to include organic compounds having the general formula RCONHz, where R is an aliphatic group having from 1-25 or more carbon atoms. These include such amides as acetamide propionamide, N-butyramide, N-valeramide, stearamide, palmitylamide, fatty acid amides and the like, Although less activity results when R is alicyclic, aromatic or mixed aliphatic aromatic, amides of this type may be used, For example, the amide may be benzamide or aromatic acid amides of the type benzene sulphonic acid amide, toluene sulphonic acid amide, naphthalene sulphonic acid amide and the like.

Best use is made when the amide is a' diamide having the general formula RzNCONRz, where R may be hydrogen or an organic radical of the type previously described for the mono-amide formula. Illustrative of suitable diamides are urea, guanidine, biuret, and the like, or N substituted ureas and unsymmetrical ureas such as N-N-dibutyl urea, N-butyl urea, N-propyl urea. dimethyl urea tertiary butyl urea, tertiary amyl urea. ethyl butyl urea and the like.

In the manufacture of cartons or separators of paper stock and the like. best use is made of the amide-nitrite corrosion inhibiting composition when the compounds are present in the ratio of about one part of the soluble nitrite to 0.05-20 parts by weight of the amide. When the composition is not to be subjected to heat treatment in the manufacture of the stock from which the carton or separator is to be produced, it is suicient if the concentration of the nitrite-amide is in the range of 1A; pound per 100 square feet of surface area to be covered. However. in the manufacture of corrugated or laminated stock for use as separators or cartons, it is best to have the original concentration calculated in the range of one pound per hundred square feet of surface area prior to heat treatment. Although higher concentrations may be used with corresponding advantage it is not economical or practical to exceed concentrations greater than ten pounds per hundred square feet. When such -concentrations are exceeded there is a tendency for the compound to chalk or powder.

This invention is directed chiefly to the manufacture of a container in the form of a corrugated carton having an inner ply or liner containing the desired concentration of corrosion inhibiting compounds. The corrosion inhibiting lcompound may be applied to the inner ply by coating, spraying, impregnation or the like from aqueous solution in the event that all of the materials are water soluble, or else in aqueous dispersion or solvent solution in suitable concentration to give the desired amount of amide-nitrite deposit with minimum treatment.

In structures of this type, when thus disposed, it appears that vapors are released from the composition which render the surfaces of the metallic compounds packaged within the container entirely free of corrosive attack by the elements normally existing in the atmosphere. It appears further that moisture plays an important part in releasing the corrosion inhibiting medium and that the shelf life or storage life of the package or separator prepared in accordance with this invention may be greatly increased by storage of the article of manufacture under substantially anhydrous conditions. It will be apparent that moisture is present under conditions of use to render the composition effective for inhibiting the normal effects of such moisture or other elements in the atmosphere which normally corrosively attack metal surfaces.

When the article of manufacture is in the form of a corrugation formed of a corrugated interlayer sandwiched between outer layers or plies of sheet stock. one or more of the outer layers may constitute the carrier for the corrosion inhibiting composition. It is suiiicient'if the layer which is to constitute the inner wall is the only impregnated layer when the corrugation is to be used in the manufacture of cartons. When the corrugation is to be used as a separator between metallic sheets it will be expedient if both of the face sheets constitute carriers for the corrosion inhibiting composition,

If, on the other hand the stock of which the carton is formed is cardboard or chip board or other laminate, the inner walls may be arranged to carry the corrosion inhibiting composition applied before or after carton manufacture from solvent solution, aqueous solution or dispersion,

or by powdery impregnation to provide the de` sired concentration of ingredients over the sinface area. Instead of making a separate impregnated sheet or carrier, the desired concentration of corrosion mhibiting composition may be laminated or adhered to the inner wall.

The system calling for the separate lamination and adherence is to be preferred in the manufacture of ber board, corrugated paper and the like, because such systems are amenable to mass production methods and the bonding agent usually employed to secure integration of the layers functions as a barrier which minimizes the transmission of vapors in either direction through the resulting stock or board. Thus, the corrosion inhibiting vapors are conned within the area most desired and the corrosion inhibiting elements normally existing in the atmosphere nd it more difficult to pass through the laminated wall and into the area in which the metallic parts are arranged.

The barrier may be further improved in a desirable manner by the use of a vapor impervious lm as an interlayer or as an outer layer of the article of manufacture. Such additional barrier may be a continuous film of plastic, metal foil, glass sheet, rubber or the like having the characteristics of low vapor transmission. When formed of plastic or rubber like material, the continuous film may be secured by conventional coating methods or by impregnation of one of the outer laminae, forming the stock of which the article of manufacture is prepared.

In the manufacture of a corrugated board, which may be used in the manufacture of cartons. interlayers, or the like, adhesive is usually applied to the adjacent faces of the outer paper plies between which the corrugated layer is to be sandwiched. The adhesive layers may be arranged to meet the corrugated layer in continuous fashion, whereupon they are pressed together and passed through the heating zone to evaporate the diluent and set the binder. Baking or heating temperatures usually employed are in the range of 250-350 F. If either the nitrite or the amide were present alone in the stock subjected to such temperature conditions, their eectiveness would be almost completely dissipated by decomposition and evaporation. When, on the 4 other hand, the amide ing composition of this invention impregnates the inner or outer plies. a substantially heat stable combination is secured with the result that its effectiveness as a corrosion inhibiting composition is not dissipated and it is able to function satisfactorily and for the purpose for which it is intended.

For the purpose of illustration but not of limitation, embodiments of this invention are shown in the accompanying drawings in which;

Figure l is a perspective view of a carton formed of corrugated paper board and embodying features of this invention.

Figure 2 is a sectional plan view indicating the manner in which a. suitable corrugated stock may be manufactured.

Figure 3 is a sectional view showing a modincation in the corrugated board which is suitable as an inner layer between metallic sheets, and

Figure 4 is a sectional view illustrating a piece of chip board embodying features of this invention.

In the manufacture of board suitable for a corrugated carton, the paper sheet which is to constitute the inner layer or ply may be 'pregnated with an aqueous solution composed of 30 parts sodium nitrite, 30 parts urea and 4G parts water. Impregnaton is arranged to clepcsit about 1 pound of amide nitrite solids it per square feet of surface area. The impregnated web I2 may be advanced directly in combination with another unimpregnated web i3 having adhesive I4 applied to their inner walls to establish a rm bond with a corrugated paper i5, fed at the same rate therebetween. The sandwiched layers are pressed together and passed through an oven heated to about 300 or 350 F. to drive oi the diluent and set the binder. The corrugated board may be stored for a considerable length of time under anhydrous conditions and it may be used in the manufacture of cartons or separators for packaging metal parts.

When the board is to be used as an interlayer or separator between metal sheet stock, it will be expedient if the layer I3 is also impregnated or provided with a suitable concentration of corrosion inhibiting composition.

Instead of impregnating the face sheets to provide impregnated layers I2 and I3, the corrosion inhibiting composition may be brushed or sprayed in suitable concentrations upon the exposed faces of the layers.

'I'hese same concepts may be embodied in a board of the type often referred to as chip board, wherein the chip board layer 2U is provided with an inner layer 2| adhered thereto and which carries about 1-3 pounds of amide nitrite per 100 square feet of surface area.

It will be understood that numerous changes may be made in the details of construction, arrangement, and operation without departing from the spirit of the invention, especially as defined in the following claims.

What is claimed is:

1. A corrugated carton wherein the inner ply has a metal corrosion inhibiting composition comprising the combination of an organic amide and an inorganic metal nitrite.

2. A corrugated carton wherein the inner ply has a metal corrosion inhibiting composition comprising the combination of an organic amide and an inorganic metal nitrite and the plies are4 nitrite corrosion inhibitn 5 secured together by applied layers of adhesive material.

3. A carton formed of integrated plies of sheet material wherein the inner ply has' a metal corrosion inhibiting composition comprising the combination of an organic amide and an inorganic metal nitrite, and a vapor barrier disposed outwardly of the inner ply.

4. A carton formed of integrated plies of sheet material wherein the inner ply has from V3 t0 l0 pounds of a metal corrosion inhibiting composition per 100 square feet of surface area, said composition comprising the combination of an organic amide and an inorganic metal nitrite present in the ratio of l part by weight nitrite to 0.05-20 parts by weight amide.

5. A corrugation formed of integrated plies of paper stock wherein the outer plies have from V3 to l0 pounds of a metal corrosion inhibiting composition per 100 square feet of surface area, said composition comprising the combination of an organic amide and an inorganic metal nitrite.

6. A carton formed of integrated plies of sheet material wherein the inner ply has a metal corrosion inhibiting composition comprising the g5 combination of urea and an alkali metal nitrite.

7. A packaging material for metal parts, the inner wall of said packaging material having a metal corrosion inhibiting composition comprising the combination of an organic amide and an inorganic metal nitrite.

8. A packaging material for metal parts, the inner wallvof said packaging material having a metal corrosion inhibiting composition comprising the combination of an organic amide and an inorganic metal nitrite present in the ratio of 1/3-10 pounds` amide-nitrite per 100 square feet of surface area.

9. A packaging for metal parts, the outer walls of said packaging material having a metal corrosion inhibiting' composition operable through vapor generation under conditions of use to inhibit corrosion of the metal parts by elements normally existing in the atmosphere and com' prising an organic amide and an inorganic metal nitrite present in the ratio of 1 part by weight nitrite to 0.05-20 parts by weight amide.

CLEMENS A. HU'I'IER.

No references cited. 

5. A CORRUGATION FORMED OF INTEGRATED PLIES OF PAPER STOCK WHEREIN TH OUTER PLIES HAVE FROM 1/3 TO 10 POUNDS OF A METAL CORROSION INHIBITING COMPOSITION PER 100 SQUARE FEET OF SURFACE AREA, SAID COMPOSITION COMPRISING THE COMBINATION OF AN ORGANIC AMIDE AND AN INORGANIC METAL NITRITE. 